How to use your 3G phone as a wireless broadband modem

By now you know about embedded and after-market 3G adapters, which provide Internet access by connecting a host (i.e., laptop, desktop, PDA) to a carrier's wireless data networks.

Embedded 3G is the most convenient option for those who require very frequent on-the-go Internet access. An after-market PC or Express card is slightly less convenient, and these small devices may be mislaid, stolen or broken. Both have a costly down-side: 3G adapters require their own service subscription, usually with a long-term contract. Going 3G this way commits you to a contract for the next year or two, depending on your carrier and data limit.

And with prices coming down on these deals - 3 has just introduced a $12/month 'Bronze' wireless data plan which includes 100MB of downloads per month and extra data at $0.10/MB - it makes little sense to commit to what could be an expensive plan.

3's new plan also shows that anyone with a 3G phone should consider using that phone as a modem. The phone won't cost you any more, after all, and gaining the flexibility to use wireless broadband for $12/month is surely a good deal if only because it can save you the cost of a wireless access card.

How to connect

The practise of linking a phone to a laptop is called 'tethering' and depending on the exact configuration of your phone and laptop, the two devices may be linked using Bluetooth, Infrared (IrDA), USB cable or serial cable. The tethered host treats the linked 3G phone as a modem, using dial-up networking or a carrier-supplied wireless connection manager to initiate calls to the carrier's network

Tethering has some downside, especially on battery life. Connecting a Bluetooth-enabled laptop to a Bluetooth-enabled smartphone is reasonably convenient but will eat into the phone's battery life. USB tethering may not consume as much handset power but requires carrying a cable and connecting it whenever Internet access is desired.

Mobile workers who need to talk on the phone while connected to the Internet cannot use one tethered handset to meet both needs simultaneously. When a laptop places a data call using a tethered modem, that phone cannot make or receive voice calls until the data session is terminated. Running a VoIP softphone on the laptop is a possible work-around but is less convenient than just using the handset directly for voice calls.

How to tether

To create a Bluetooth dial-up networking connection (illustrated below), just enable Bluetooth on both the laptop and phone, then tell the laptop to discover nearby devices. Search the discovered phone for supported services, one of which will be dial-up networking. Configure that service with the carrier-specified dial-up parameters (username, password, phone number) and a new Bluetooth connection will appear on the Network Connections panel.

USB tethering is slightly more involved. Driver files must be copied onto the laptop before connecting the phone to the laptop's USB port. The phone itself must be set to activate the modem link on the USB port. Upon first connect, Windows XP launches the new hardware wizard to install drivers for the phone. Once that hardware has been successfully installed, a dial-up networking connection can be manually configured with the same parameters described for Bluetooth above.

As an alternative to manual dial-up network connections, you may wish to use a carrier-supplied wireless connection manager. The following figure illustrates Verizon's VZAccess Manager being used to control a tethered Motorola Q connection. Connection managers are ideal for laptops with multiple network connections -- for example, automatically using corporate Wi-Fi networks whenever they are near, then switching over to 3G or 2.5G services where no Wi-Fi signal is detected.

Conclusion

Many workers do not even realize that tethering a laptop to a 3G phone is an option. While tethering may not be as seamless as a dedicated 3G wireless adapter, potential savings can more than make up for the inconvenience. Tethering is certainly not the best option for every mobile professional. But, given simple set-up and low entry cost, 3G phone tethering should certainly be considered as one possible alternative for laptop Internet access.

About the author:

Lisa A. Phifer is vice president of Core Competence Inc. She has been involved in the design, implementation and evaluation of data communications, internetworking, security and network management products for more than 20 years and has advised companies large and small regarding security needs, product assessment and the use of emerging technologies and best practices

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